The overall objectives of the research project are to study the mechanisms of the interaction of bacteria with receptors in the membranes of epithelial cells of mucosal surfaces. Studies will focus upon: (a) identifying more precisely the bacterial ligands involved in the adherence of the organisms to membrane receptors on the surface of epithelial cells, and (b) to isolate and characterize the membrane receptors which serve to attach bacteria to mucosal surfaces. Initially our studies will be limited to streptococci and E. coli. We have already demonstrated that the bacterial ligand of group A streptococci is lipoteichoic acid and the membrane receptor for attachment of E. coli to host cells bears mannose residues. It is hoped that these studies will shed light upon the mechanisms by which bacterial colonize mucosal surfaces to set up the infectious process. An understanding of these mechanisms may lead to the development of methods for the prevention of the infectious process before the bacteria gain a foothold on mucosal surfaces to cause tissue injury.